Everything in this chapter is the substrate for the next chapter on Pulse and Digital Circuits and the chapter after that on Computer Architecture. Let me sketch how the pieces fit before we move on.
A simple processor has:
- A register file: a bank of D flip-flops accessed through muxes (read ports) and decoders (write port). Section 5.8.
- An ALU: an arithmetic-and-logic block from Section 5.12.
- Status flags: combinational outputs of the ALU stored in 1-bit D flip-flops.
- A program counter: a synchronous up-counter, loadable for jumps. Sections 7.4 and 8.2.
- An instruction register: a parallel-in register loaded from memory. Section 9.4.
- A control FSM: a Moore (or Mealy) state machine that walks through fetch, decode, execute, writeback. Section 10.
That is a CPU, in skeleton. Add memory, interrupts, and pipelining, and you have something that runs C. This is Computer Architecture in three sentences, and every sentence is built from the parts of this chapter.